For all of the years that sailing ships and boats have been sailing the seas, there has always been a need for climbing the masts of such vessels. In early times the large ships had ratlines for climbing up on the rigging to reach the top of the mast. A sailor of smaller vessels was typically hauled up the mast by a borun's chair, which required at least one other person.
In more recent years, step devices have been used to climb a sailboat mast. These steps are typically made of aluminum, come in a variety of styles, and are permanently attached to the mast. The steps are arranged on the mast in coordinating left/right fashion so that a sailor can climb to the top of the mast. Some of the step devices fold up onto the sides of the mast when not in use. An article entitled "Stairway to Heaven" illustrates and describes steps that are currently in use today.